aspirin + phenacetin + caffeine

Zhitong San (止痛散) is a classic analgesic and antipyretic combination medication widely used in China, commonly referred to as APC powder. It is composed of three active pharmaceutical ingredients: aspirin, phenacetin, and caffeine. Aspirin and phenacetin function as nonsteroidal anti-inflammatory drugs (NSAIDs) that provide pain relief and reduce fever by inhibiting cyclooxygenase enzymes and subsequent prostaglandin synthesis. Caffeine is included as an adjuvant to enhance the analgesic efficacy of the NSAIDs and to provide a mild stimulant effect. While historically popular for the treatment of headaches, toothaches, and neuralgia, the use of Zhitong San has faced scrutiny due to the phenacetin component, which is associated with nephrotoxicity and urothelial carcinoma upon long-term use. Consequently, it has been largely superseded by safer combinations (such as those containing paracetamol) in many clinical guidelines, though it remains available in the Chinese market.

Brand names

Zhitong San止痛散

Other names

APC powderAspirin, Phenacetin and Caffeine Powder阿司匹林非那西丁咖啡因散Headache Powder头痛粉